diff --git a/lib/serializer.js b/lib/serializer.js
index 1ad588a1..24917433 100644
--- a/lib/serializer.js
+++ b/lib/serializer.js
@@ -24,38 +24,29 @@ module.exports = class Serializer {
   }
 
   asInteger (i) {
-    if (typeof i === 'number') {
-      if (Number.isInteger(i)) {
-        return '' + i
-      }
-      // check if number is Infinity or NaN
-      // eslint-disable-next-line no-self-compare
-      if (i === Infinity || i === -Infinity || i !== i) {
-        throw new Error(`The value "${i}" cannot be converted to an integer.`)
-      }
-      return this.parseInteger(i)
-    } else if (i === null) {
-      return '0'
+    if (Number.isInteger(i)) {
+      return '' + i
     } else if (typeof i === 'bigint') {
       return i.toString()
-    } else {
-      /* eslint no-undef: "off" */
-      const integer = this.parseInteger(i)
-      if (Number.isFinite(integer)) {
-        return '' + integer
-      } else {
-        throw new Error(`The value "${i}" cannot be converted to an integer.`)
-      }
     }
+    /* eslint no-undef: "off" */
+    const integer = this.parseInteger(i)
+    // check if number is Infinity or NaN
+    // eslint-disable-next-line no-self-compare
+    if (integer === Infinity || integer === -Infinity || integer !== integer) {
+      throw new Error(`The value "${i}" cannot be converted to an integer.`)
+    }
+    return '' + integer
   }
 
   asNumber (i) {
-    const num = Number(i)
+    // fast cast to number
+    const num = +i
     // check if number is NaN
     // eslint-disable-next-line no-self-compare
     if (num !== num) {
       throw new Error(`The value "${i}" cannot be converted to a number.`)
-    } else if (!Number.isFinite(num)) {
+    } else if (num === Infinity || num === -Infinity) {
       return 'null'
     } else {
       return '' + num
@@ -100,9 +91,34 @@ module.exports = class Serializer {
   }
 
   asString (str) {
-    if (str.length < 42) {
-      return this.asStringSmall(str)
-    } else if (str.length < 5000 && STR_ESCAPE.test(str) === false) {
+    const len = str.length
+    if (len < 42) {
+      // magically escape strings for json
+      // relying on their charCodeAt
+      // everything below 32 needs JSON.stringify()
+      // every string that contain surrogate needs JSON.stringify()
+      // 34 and 92 happens all the time, so we
+      // have a fast case for them
+      let result = ''
+      let last = -1
+      let point = 255
+      // eslint-disable-next-line
+      for (var i = 0; i < len; i++) {
+        point = str.charCodeAt(i)
+        if (
+          point === 0x22 || // '"'
+          point === 0x5c // '\'
+        ) {
+          last === -1 && (last = 0)
+          result += str.slice(last, i) + '\\'
+          last = i
+        } else if (point < 32 || (point >= 0xD800 && point <= 0xDFFF)) {
+          // The current character is non-printable characters or a surrogate.
+          return JSON.stringify(str)
+        }
+      }
+      return (last === -1 && ('"' + str + '"')) || ('"' + result + str.slice(last) + '"')
+    } else if (len < 5000 && STR_ESCAPE.test(str) === false) {
       // Only use the regular expression for shorter input. The overhead is otherwise too much.
       return '"' + str + '"'
     } else {
@@ -114,37 +130,6 @@ module.exports = class Serializer {
     return '"' + str + '"'
   }
 
-  // magically escape strings for json
-  // relying on their charCodeAt
-  // everything below 32 needs JSON.stringify()
-  // every string that contain surrogate needs JSON.stringify()
-  // 34 and 92 happens all the time, so we
-  // have a fast case for them
-  asStringSmall (str) {
-    const len = str.length
-    let result = ''
-    let last = -1
-    let point = 255
-
-    // eslint-disable-next-line
-    for (var i = 0; i < len; i++) {
-      point = str.charCodeAt(i)
-      if (
-        point === 0x22 || // '"'
-        point === 0x5c // '\'
-      ) {
-        last === -1 && (last = 0)
-        result += str.slice(last, i) + '\\'
-        last = i
-      } else if (point < 32 || (point >= 0xD800 && point <= 0xDFFF)) {
-        // The current character is non-printable characters or a surrogate.
-        return JSON.stringify(str)
-      }
-    }
-
-    return (last === -1 && ('"' + str + '"')) || ('"' + result + str.slice(last) + '"')
-  }
-
   getState () {
     return this._options
   }